A meeting with AIDS activists at the height of the epidemic galvanized Anthony Fauci. He is now America's most tireless champion of their cause

The year was 1988, and the U.S. AIDS epidemic was in full bloom. Angry homosexual groups were blaming the National Institute of Allergy and Infectious Diseases (NIAID) for the glacial pace of government research, drug testing and drug approval. Dr. Anthony Fauci, director of the agency since 1984, was singled out for attack, branded a "Nazi" and a "murderer," and hanged in effigy.

Other government officials might have hunkered down. But Fauci decided to hear his critics out. Meeting with AIDS activists in San Francisco, he was introduced to a 34-year-old schoolteacher who explained that a maze of outdated government...